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Dynamical separation of spherical bodies in supersonic flow

Dynamical separation of spherical bodies in supersonic flow
Dynamical separation of spherical bodies in supersonic flow
An experimental and computational investigation of the unsteady separation behaviour of two spheres in Mach-4 flow is carried out. The spherical bodies, initially contiguous, are released with negligible relative velocity and thereafter fly freely according to the aerodynamic forces experienced. In experiments performed in a supersonic Ludwieg tube, nylon spheres are initially suspended in the test section by weak threads which are detached by the arrival of the flow. The subsequent sphere motions and unsteady flow structures are recorded using high-speed (13 kHz) focused shadowgraphy. The qualitative separation behaviour and the final lateral velocity of the smaller sphere are found to vary strongly with both the radius ratio and the initial alignment angle of the two spheres. More disparate radii and initial configurations in which the smaller sphere centre lies downstream of the larger sphere centre each increases the tendency for the smaller sphere to be entrained within the flow region bounded by the bow shock of the larger body, rather than expelled from this region. At a critical angle for a given radius ratio (or a critical radius ratio for a given angle), transition from entrainment to expulsion occurs; at this critical value, the final lateral velocity is close to maximum due to the same ‘surfing’ effect noted by Laurence & Deiterding (J. Fluid Mech., vol. 676, 2011, pp. 396–431) at hypersonic Mach numbers. A visualization-based tracking algorithm is used to provide quantitative comparisons between the experiments and high-resolution inviscid numerical simulations, with generally favourable agreement.
aerodynamics, flow–structure interactions, shock waves
0022-1120
159-182
Laurence, Stuart J.
c9870caa-b37e-4ee1-b4a4-3b348c2f9bc0
Parziale, Nick J.
99ac657e-78db-4f6b-8241-0a82948c3b3b
Deiterding, Ralf
ce02244b-6651-47e3-8325-2c0a0c9c6314
Laurence, Stuart J.
c9870caa-b37e-4ee1-b4a4-3b348c2f9bc0
Parziale, Nick J.
99ac657e-78db-4f6b-8241-0a82948c3b3b
Deiterding, Ralf
ce02244b-6651-47e3-8325-2c0a0c9c6314

Laurence, Stuart J., Parziale, Nick J. and Deiterding, Ralf (2012) Dynamical separation of spherical bodies in supersonic flow. Journal of Fluid Mechanics, 713, 159-182. (doi:10.1017/jfm.2012.453).

Record type: Article

Abstract

An experimental and computational investigation of the unsteady separation behaviour of two spheres in Mach-4 flow is carried out. The spherical bodies, initially contiguous, are released with negligible relative velocity and thereafter fly freely according to the aerodynamic forces experienced. In experiments performed in a supersonic Ludwieg tube, nylon spheres are initially suspended in the test section by weak threads which are detached by the arrival of the flow. The subsequent sphere motions and unsteady flow structures are recorded using high-speed (13 kHz) focused shadowgraphy. The qualitative separation behaviour and the final lateral velocity of the smaller sphere are found to vary strongly with both the radius ratio and the initial alignment angle of the two spheres. More disparate radii and initial configurations in which the smaller sphere centre lies downstream of the larger sphere centre each increases the tendency for the smaller sphere to be entrained within the flow region bounded by the bow shock of the larger body, rather than expelled from this region. At a critical angle for a given radius ratio (or a critical radius ratio for a given angle), transition from entrainment to expulsion occurs; at this critical value, the final lateral velocity is close to maximum due to the same ‘surfing’ effect noted by Laurence & Deiterding (J. Fluid Mech., vol. 676, 2011, pp. 396–431) at hypersonic Mach numbers. A visualization-based tracking algorithm is used to provide quantitative comparisons between the experiments and high-resolution inviscid numerical simulations, with generally favourable agreement.

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More information

Published date: 26 October 2012
Keywords: aerodynamics, flow–structure interactions, shock waves
Organisations: Aerodynamics & Flight Mechanics Group

Identifiers

Local EPrints ID: 380643
URI: http://eprints.soton.ac.uk/id/eprint/380643
ISSN: 0022-1120
PURE UUID: c6702ef4-7d22-43df-934d-79a3cde7ec2c
ORCID for Ralf Deiterding: ORCID iD orcid.org/0000-0003-4776-8183

Catalogue record

Date deposited: 08 Sep 2015 16:16
Last modified: 15 Mar 2024 03:52

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Contributors

Author: Stuart J. Laurence
Author: Nick J. Parziale
Author: Ralf Deiterding ORCID iD

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